Macular degeneration: The general term for eye diseases in which the central part of the light-sensitive tissue in the eye that sends visual messages to brain is destroyed.
Macular degeneration is a group of eye diseases that affect central vision. According to the National Eye Institute, it is the leading cause of severe vision loss among people age 65 and older, especially among Caucasians. The disease tends to occur more often in women than in men.
Macular degeneration often is called age-related macular degeneration (AMD) because the greatest risk factor for the disease is advancing age. Although AMD can occur in middle age, studies show that people age 65 and older are at greatest risk for developing AMD. Results reported of a 10-year University of Wisconsin study involving 3,583 patients found that people age 65 and older are more than 80 times more likely to develop the disease than those ages 55-64. That study also found an increased risk among women compared to men. The National Eye Institute reports that 13 million people in the United States have signs of macular degeneration.
Some forms of macular degeneration can occur in children. One is juvenile macular degeneration, or Stargardt's disease, which affects one in 10,000 children, according to the American Macular Degeneration Foundation; it usually appears between the ages of seven and 12 and is inherited. A gene that causes Stargardt's disease has been identified.
Genetic and other risk factorsA 1997 study conducted by teams of scientists with the National Cancer Institute's Frederick Cancer Research and Development Center in Maryland discovered a genetic component to this disease.
As the federal government's lead agency on vision research and sponsor of continuing studies on AMD, the National Eye Institute says its research so far also indicates the following additional risks for macular degeneration:
obesity (Research studies suggest a link between obesity and the progression of early- and intermediate-stage AMD to advanced AMD.)
Caucasian ethnicity
being female
a family history of the condition
smoking
high blood cholesterol levels
cardiovascular disease
hypertension
farsightedness
light colored eyes
SymptomsMacular degeneration affects the macula, the central part of the retina of the eye that allows you to see fine, sharp details straight ahead. The retina is made of light-sensitive tissue that sends visual messages via nerve impulses to the brain through the optic nerve. The brain then processes the nerve signals into a "picture" that you see. The macula consists of millions of light-sensitive cells that help provide the central vision used in reading, driving, recognizing faces, and doing close work, such as sewing. As the macula deteriorates, central vision becomes blurred and distorted. Difficulty reading, distortion of letters, a greater need for more light to see, reduced color vision and the loss of ability to see fine detail are other symptoms of macular degeneration. Pain is not a symptom. Although peripheral, or side, vision usually is not affected by macular degeneration, and people rarely go totally blind from the disease, it can severely hamper daily activities because of the loss of fine, central sight.
The two common types of macular degeneration are "dry" and "wet." According to the National Eye Institute, about 90 percent of people who have macular degeneration have the dry, or atrophic, form. The light-sensitive cells in the macula slowly break down in this form of the disease, resulting in a gradual loss of central vision over a period of many years. Dry macular degeneration often first occurs in just one eye. The disease may or may not affect the other eye later. Although researchers continue to study the disease, the exact cause of dry macular degeneration is unknown, and there is no cure. There also is no effective treatment to stop the gradual loss of detailed central vision. However, studies suggest that high dose vitamins C, E, beta carotene, and zinc (along with copper) can reduce the risk of both wet and dry AMD as much as 25 percent.
The early warning sign of dry macular degeneration is blurred vision. As cells in the macula deteriorate, fewer details can be seen clearly when looking straight ahead. Often, bright light, by improving contrast, can enable patients to see better, although their vision will still be blurred. As the light-sensitive cells die, a small blind spot may appear in the middle of the vision field. Over the course of many years, the blind spot may increase in size with an accompanying decrease in the central visual acuity.
The wet form of macular degeneration occurs only in about 10 percent of people with the disease, but it accounts for 90 percent of all severe vision loss from AMD, according to the National Eye Institute. The wet form occurs when new, abnormal blood vessels grow in or under the retina. The blood vessel growth is called Subretinal or choroidal neovascularization or angiogenesis. These weak blood vessels may leak fluid and bleed, causing the macula to bulge or lift up in the eye, damaging it and distorting vision. This produces the classic early symptom of straight lines appearing wavy. As with dry macular degeneration, this may produce the symptom of straight lines appearing wavy. Wet macular degeneration may also cause a blind spot to develop. Central vision can be destroyed in a short period of time, sometimes as fast as within weeks to months, or it can take longer.
Macular degeneration is a group of eye diseases that affect central vision. According to the National Eye Institute, it is the leading cause of severe vision loss among people age 65 and older, especially among Caucasians. The disease tends to occur more often in women than in men.
Macular degeneration often is called age-related macular degeneration (AMD) because the greatest risk factor for the disease is advancing age. Although AMD can occur in middle age, studies show that people age 65 and older are at greatest risk for developing AMD. Results reported of a 10-year University of Wisconsin study involving 3,583 patients found that people age 65 and older are more than 80 times more likely to develop the disease than those ages 55-64. That study also found an increased risk among women compared to men. The National Eye Institute reports that 13 million people in the United States have signs of macular degeneration.
Some forms of macular degeneration can occur in children. One is juvenile macular degeneration, or Stargardt's disease, which affects one in 10,000 children, according to the American Macular Degeneration Foundation; it usually appears between the ages of seven and 12 and is inherited. A gene that causes Stargardt's disease has been identified.
Genetic and other risk factorsA 1997 study conducted by teams of scientists with the National Cancer Institute's Frederick Cancer Research and Development Center in Maryland discovered a genetic component to this disease.
As the federal government's lead agency on vision research and sponsor of continuing studies on AMD, the National Eye Institute says its research so far also indicates the following additional risks for macular degeneration:
obesity (Research studies suggest a link between obesity and the progression of early- and intermediate-stage AMD to advanced AMD.)
Caucasian ethnicity
being female
a family history of the condition
smoking
high blood cholesterol levels
cardiovascular disease
hypertension
farsightedness
light colored eyes
SymptomsMacular degeneration affects the macula, the central part of the retina of the eye that allows you to see fine, sharp details straight ahead. The retina is made of light-sensitive tissue that sends visual messages via nerve impulses to the brain through the optic nerve. The brain then processes the nerve signals into a "picture" that you see. The macula consists of millions of light-sensitive cells that help provide the central vision used in reading, driving, recognizing faces, and doing close work, such as sewing. As the macula deteriorates, central vision becomes blurred and distorted. Difficulty reading, distortion of letters, a greater need for more light to see, reduced color vision and the loss of ability to see fine detail are other symptoms of macular degeneration. Pain is not a symptom. Although peripheral, or side, vision usually is not affected by macular degeneration, and people rarely go totally blind from the disease, it can severely hamper daily activities because of the loss of fine, central sight.
The two common types of macular degeneration are "dry" and "wet." According to the National Eye Institute, about 90 percent of people who have macular degeneration have the dry, or atrophic, form. The light-sensitive cells in the macula slowly break down in this form of the disease, resulting in a gradual loss of central vision over a period of many years. Dry macular degeneration often first occurs in just one eye. The disease may or may not affect the other eye later. Although researchers continue to study the disease, the exact cause of dry macular degeneration is unknown, and there is no cure. There also is no effective treatment to stop the gradual loss of detailed central vision. However, studies suggest that high dose vitamins C, E, beta carotene, and zinc (along with copper) can reduce the risk of both wet and dry AMD as much as 25 percent.
The early warning sign of dry macular degeneration is blurred vision. As cells in the macula deteriorate, fewer details can be seen clearly when looking straight ahead. Often, bright light, by improving contrast, can enable patients to see better, although their vision will still be blurred. As the light-sensitive cells die, a small blind spot may appear in the middle of the vision field. Over the course of many years, the blind spot may increase in size with an accompanying decrease in the central visual acuity.
The wet form of macular degeneration occurs only in about 10 percent of people with the disease, but it accounts for 90 percent of all severe vision loss from AMD, according to the National Eye Institute. The wet form occurs when new, abnormal blood vessels grow in or under the retina. The blood vessel growth is called Subretinal or choroidal neovascularization or angiogenesis. These weak blood vessels may leak fluid and bleed, causing the macula to bulge or lift up in the eye, damaging it and distorting vision. This produces the classic early symptom of straight lines appearing wavy. As with dry macular degeneration, this may produce the symptom of straight lines appearing wavy. Wet macular degeneration may also cause a blind spot to develop. Central vision can be destroyed in a short period of time, sometimes as fast as within weeks to months, or it can take longer.
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